1. Field of the Invention
The present invention relates to drive systems for adjusting the position of remotely controlled electrically operated automotive rear view mirrors, and more particularly to an improved actuator shaft for such drive systems.
2. Description of the Prior Art
The use of electrically operated remote control means to adjust the position of an outside rear view mirror is well known in the art. It is also known, in such control means to use electrically driven rotatable nuts which cause longitudinal nonrotary movement of two screws which engage the backing plate of the mirror to cause it to pivot about each of two mutually perpendicular axes. The rotatable nuts may be driven by either a single motor driven worm gear which selectively pivots into engagement with one or the other of the nuts or by two sets of motors and worm gears.
An override feature is commonly provided by which the motor is permitted to continue to run after the mirror has reached the limit of its movement, or, conversely, the mirror can be manually shifted when the motor is not operating. Such override features have been achieved, for example, by the use of a split nut which permits the nut to rotate without causing longitudinal movement of the screw or permits the screw to move longitudinally without rotation of the nut. The segments of the split nut are resiliently biased in a radially inward direction to normally maintain a driving engagement with the threads of the screw. However, in an overload condition, the nut segments resiliently yield radially outwardly to disengage the driving relationship between the screw and the nut threads. Such a drive system may be found in U.S. Pat. No. 4,041,793.
Alternatively, it is known to use an adjustable screw with threaded segments that are inwardly biased to disengage a rotatable nut in such an overload condition. Exemplary of such an adjustable drive shaft is the drive system found in German Pat. No. 2840789.
It is further known to provide means to adjust the drive mechanism to account for the degree of travel of the mirror along its arc of pivotable movement. U.S. Pat. No. 4,482,211 discloses such an improved system in the use of a three piece assembly comprising a worm gear driven pinion gear having a spherical socket which receives a ball shaped drive nut splined for co-axial rotation with the pinion gear, and internally threaded to receive a screw member having radially inwardly and resiliently yieldable male thread segments. The ball-socket relationship of the pinion gear and nut permit the axis of the nut, and therefore the axis of the screw, to pivot or skew relative to the fixed axis of the pinion gear, while the splined connection between the spherically socketed bore of the pinion gear and the ball shaped exterior of the nut permit uniform simultaneous rotation of such members whether their axis are co-axial or skewed. Thus, the connection of the screw to the mirror can follow the arcuate travel of the mirror as its position is adjusted by the screws, with a smooth and uniform driving relationship irrespective of the angle of the mirror.
The present invention is directed to the creation of an improved and greatly simplified drive system which operates reliably, smoothly, and efficiently.